Machines, such as, scrapers, typically include a tractor connected to a bowl having a blade configured to separate material from a surface of terrain over which the scraper traverses. Both the tractor and the bowl are usually supported on the surface via respective traction devices and an operator usually controls the direction and speed at which the scraper traverses the surface. The blade is typically located in the forward position of the bowl and adjacent the surface, and an operator usually controls the position of the bowl relative to the surface via one or more actuators. By lowering the bowl and driving the tractor over the surface, an operator can engage the blade with the surface of the terrain to dislodge the material and divert the dislodged material into the bowl. After an operator loads the bowl to its full capacity, the operator raises the bowl and transports the material to another location for unloading.
Varying terrain topography, material characteristics, and scraper speed can impact the ability of the scraper to dislodge and load material. Typically, manual control of a scraper with respect to these changing parameters is complicated, requires a significant amount of operator skill, and may be ergonomically difficult, all of which may adversely affect operator safety. Often, an operator adjusts the depth the blade engages and/or penetrates the surface and the speed of the scraper in response to the changing parameters to operate the scraper within a desirable set of conditions, e.g., below an engine torque limit, while speedily loading the bowl.
U.S. Pat. No. 6,125,561 (“the '561 patent”) issued to Shull discloses a method for automatic loading of a scraper bowl. The method of the '561 patent includes sensing a force applied to the scraper bowl transmitted thereto via a scraper blade. The method of the '561 patent determines a time dependent error signal as a function of the sensed force and a target force. The method of the '561 patent determines a position command signal as a function of the error signal that is used to automatically adjust the depth of cut of the scraper blade. Additionally, the method of the '561 patent may determine when the scraper bowl is full as a function of the time component associated with the time dependent error signal, a set time limit, and the time when the limit is reached.
Although, the method of the '561 patent may automatically adjust the depth of the cutting blade as a function of target and sensed forces acting on the scraper, considering additional parameters may improve the responsiveness and/or accuracy of the scraper blade control. In addition, the method of the '561 patent is based on controlling the forces transmitted by the scraper blade and determines such forces via hydraulic cylinder pressures which may, however, reduce the accuracy of the determined forces.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.